BIAS

A statistical term describing a systematic inﬂuence which leads to consistent over- or underestimation of the true value. For example, if a researcher is studying the eﬀects of two diﬀerent drugs on the same disease and personally favours one, unless they have been blinded to which patient is receiving which treatment, they may unwittingly cause bias in the results by regarding those treated with their preferred drug as being healthier.